Australian Energy Market Operator

AEMO operates Australia's National Electricity Market (NEM), the interconnected power system in Australia’s eastern and south-eastern seaboard, and the Wholesale Electricity Market (WEM) and power system in Western Australia.

AEMO operates gas retail markets in New South Wales and the Australian Capital Territory, Queensland, South Australia, Victoria, and Western Australia. AEMO also operates wholesale gas markets in south-eastern Australia, those being the Declared Wholesale Gas Market in Victoria (DWGM), the Short Term Trading Market in Adelaide, Brisbane and Sydney (STTM), and the Gas Supply Hub (GSH), whose trading locations are based at Wallumbilla in Queensland, and Moomba in South Australia. AEMO also operates the Natural Gas Services Bulletin Board (GBB), and is system operator of the Victorian Gas Declared Transmission System. AEMO is also responsible for Gas Services Information functions in Western Australia.

Where the technical limits of a distribution system will be exceeded and the rectification options are likely to exceed $10M, Ergon Energy is required under the National Electricity Rules s5.6.2(f) to consult with affected Registered Participants, AEMO and Interested Parties within the time required for corrective action and meet certain requirements, including undertaking analysis that satisfies the AER’s Regulatory Test, in selection of an appropriate solution.

Ergon Energy Corporation Limited (Ergon Energy) is responsible (under its Distribution Authority) for electricity supply to the Central Toowoomba area in southern Queensland. We have identified emerging limitations in the electricity distribution network supplying the central Toowoomba area. The loads on Ergon Energy’s aged and poor condition Central Toowoomba zone substation has progressively increased such that augmentation is required if reliable supply is to be maintained.

In order to ensure that supply to customers in the central Toowoomba area complies with Ergon Energy’s security of supply criteria, corrective action will be required to be completed prior to the summer of 2014/15.

Ergon Energy published a Request for Information relating to this emerging network constraint on 20 December 2012. No submissions were received by the closing date of 14 February 2013.

Ergon Energy published a Consultation and Draft Recommendation on 4 April 2013 relating to this emerging network constraint. No submissions were received by the closing date of 2 May 2013.

Two feasible solutions to the emerging network constraint have been identified:

Option 1 Rebuild the Central Toowoomba sub at 110/11kV

Option 2 Rebuild the Central Toowoomba sub at 33/11kV

Ergon Energy’s recommended action is Option 1. The estimated cost of this option is $41,000,000, and it is planned to be completed by December 2014.